ABOUT THE SPEAKER
Dustin Schroeder - Radio glaciologist
Dustin Schroeder develops and uses geophysical radar to study Antarctica, Greenland and the icy moons of Jupiter.

Why you should listen

Dustin Schroeder draws on techniques and approaches from defense technologies, telecommunication, resource exploration and radio astronomy to understand the evolution and stability of ice sheets and their contributions to sea level rise. He is an assistant professor of geophysics and (by courtesy) of electrical engineering at Stanford University where he is also an affiliate of the Woods Institute for the Environment. He has participated in three Antarctic field seasons with the ICECAP project and NASA’s Operation Ice Bridge.

Schroeder is a Science Team Member on the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) instrument on NASA's Europa Clipper Mission and the Mini-RF instrument on NASA's Lunar Reconnaissance Orbiter (LRO). He is also the Chair of the Earth and Space Sciences Committee for the National Science Olympiad.

More profile about the speaker
Dustin Schroeder | Speaker | TED.com
TEDxStanford

Dustin Schroeder: How we look kilometers below the Antarctic ice sheet

Filmed:
969,568 views

Antarctica is a vast and dynamic place, but radar technologies -- from World War II-era film to state-of-the-art miniaturized sensors -- are enabling scientists to observe and understand changes beneath the continent's ice in unprecedented detail. Join radio glaciologist Dustin Schroeder on a flight high above Antarctica and see how ice-penetrating radar is helping us learn about future sea level rise -- and what the melting ice will mean for us all.
- Radio glaciologist
Dustin Schroeder develops and uses geophysical radar to study Antarctica, Greenland and the icy moons of Jupiter. Full bio

Double-click the English transcript below to play the video.

00:12
I'm a radio glaciologist.
0
929
2087
00:15
That means that I use radar
to study glaciers and ice sheets.
1
3397
3872
00:19
And like most glaciologists right now,
2
7705
2023
00:21
I'm working on the problem of estimating
3
9752
2068
00:23
how much the ice is going to contribute
to sea level rise in the future.
4
11844
4160
00:28
So today, I want to talk to you about
5
16367
1775
00:30
why it's so hard to put good numbers
on sea level rise,
6
18166
3737
00:33
and why I believe that by changing
the way we think about radar technology
7
21927
4040
00:37
and earth-science education,
8
25991
1388
00:39
we can get much better at it.
9
27403
1754
00:42
When most scientists
talk about sea level rise,
10
30030
2302
00:44
they show a plot like this.
11
32356
1381
00:45
This is produced using ice sheet
and climate models.
12
33761
2786
00:48
On the right, you can see
the range of sea level
13
36966
2341
00:51
predicted by these models
over the next 100 years.
14
39331
3198
00:54
For context, this is current sea level,
15
42553
2952
00:57
and this is the sea level
16
45529
1398
00:58
above which more than 4 million people
could be vulnerable to displacement.
17
46951
3554
01:02
So in terms of planning,
18
50863
1770
01:04
the uncertainty in this plot
is already large.
19
52657
3182
01:07
However, beyond that, this plot comes
with the asterisk and the caveat,
20
55863
4674
01:12
"... unless the West Antarctic
Ice Sheet collapses."
21
60561
2921
01:15
And in that case, we would be talking
about dramatically higher numbers.
22
63506
3563
01:19
They'd literally be off the chart.
23
67093
1968
01:21
And the reason we should take
that possibility seriously
24
69671
3065
01:24
is that we know from the geologic
history of the Earth
25
72760
2580
01:27
that there were periods in its history
26
75364
2158
01:29
when sea level rose
much more quickly than today.
27
77546
2641
01:32
And right now, we cannot rule out
28
80211
2025
01:34
the possibility of that
happening in the future.
29
82260
2452
01:37
So why can't we say with confidence
30
85625
3136
01:40
whether or not a significant portion
of a continent-scale ice sheet
31
88785
5197
01:46
will or will not collapse?
32
94006
2101
01:48
Well, in order to do that, we need models
33
96799
1985
01:50
that we know include all of the processes,
conditions and physics
34
98808
3581
01:54
that would be involved
in a collapse like that.
35
102413
2398
01:57
And that's hard to know,
36
105206
1460
01:58
because those processes
and conditions are taking place
37
106690
2734
02:01
beneath kilometers of ice,
38
109448
1839
02:03
and satellites, like the one
that produced this image,
39
111311
2550
02:05
are blind to observe them.
40
113885
1425
02:07
In fact, we have much more comprehensive
observations of the surface of Mars
41
115713
4284
02:12
than we do of what's beneath
the Antarctic ice sheet.
42
120021
2662
02:15
And this is even more challenging
in that we need these observations
43
123829
3207
02:19
at a gigantic scale
in both space and time.
44
127060
3196
02:22
In terms of space, this is a continent.
45
130687
2248
02:25
And in the same way that in North America,
46
133322
2120
02:27
the Rocky Mountains, Everglades
and Great Lakes regions are very distinct,
47
135466
4040
02:31
so are the subsurface
regions of Antarctica.
48
139530
2991
02:34
And in terms of time, we now know
49
142545
1643
02:36
that ice sheets not only evolve over
the timescale of millennia and centuries,
50
144212
4341
02:40
but they're also changing
over the scale of years and days.
51
148577
3786
02:44
So what we want is observations
beneath kilometers of ice
52
152387
4309
02:48
at the scale of a continent,
53
156720
1929
02:50
and we want them all the time.
54
158673
1645
02:53
So how do we do this?
55
161014
1400
02:54
Well, we're not totally blind
to the subsurface.
56
162814
4056
02:58
I said in the beginning
that I was a radio glaciologist,
57
166894
2670
03:01
and the reason that that's a thing
58
169588
1878
03:03
is that airborne ice-penetrating radar
is the main tool we have
59
171490
3770
03:07
to see inside of ice sheets.
60
175284
1596
03:09
So most of the data used by my group
is collected by airplanes
61
177212
3846
03:13
like this World War II-era DC-3,
62
181082
2225
03:15
that actually fought
in the Battle of the Bulge.
63
183331
2452
03:17
You can see the antennas
underneath the wing.
64
185807
2580
03:20
These are used to transmit
radar signals down into the ice.
65
188411
3730
03:24
And the echos that come back
contain information
66
192165
2453
03:26
about what's happening inside
and beneath the ice sheet.
67
194642
2937
03:30
While this is happening,
68
198530
1317
03:31
scientists and engineers
are on the airplane
69
199871
2285
03:34
for eight hours at a stretch,
70
202180
1487
03:35
making sure that the radar's working.
71
203691
1869
03:37
And I think this is actually
a misconception
72
205996
2541
03:40
about this type of fieldwork,
73
208561
1444
03:42
where people imagine
scientists peering out the window,
74
210029
3147
03:45
contemplating the landscape,
its geologic context
75
213200
2914
03:48
and the fate of the ice sheets.
76
216138
1718
03:50
We actually had a guy from the BBC's
"Frozen Planet" on one of these flights.
77
218327
3623
03:53
And he spent, like, hours
videotaping us turn knobs.
78
221974
2722
03:57
(Laughter)
79
225046
2603
03:59
And I was actually watching the series
years later with my wife,
80
227673
3376
04:03
and a scene like this came up,
and I commented on how beautiful it was.
81
231073
3423
04:07
And she said, "Weren't you
on that flight?"
82
235001
2930
04:09
(Laughter)
83
237955
1159
04:11
I said, "Yeah, but I was looking
at a computer screen."
84
239138
2945
04:14
(Laughter)
85
242107
1256
04:15
So when you think
about this type of fieldwork,
86
243387
2207
04:17
don't think about images like this.
87
245618
2023
04:19
Think about images like this.
88
247665
1691
04:21
(Laughter)
89
249380
1163
04:22
This is a radargram, which is
a vertical profile through the ice sheet,
90
250567
3342
04:25
kind of like a slice of cake.
91
253933
1484
04:27
The bright layer on the top
is the surface of the ice sheet,
92
255768
2849
04:30
the bright layer on the bottom
is the bedrock of the continent itself,
93
258641
3330
04:33
and the layers in between
are kind of like tree rings,
94
261995
2526
04:36
in that they contain information
about the history of the ice sheet.
95
264545
3207
04:39
And it's amazing
that this works this well.
96
267776
2230
04:42
The ground-penetrating
radars that are used
97
270321
2018
04:44
to investigate infrastructures of roads
or detect land mines
98
272363
2928
04:47
struggle to get through
a few meters of earth.
99
275315
2159
04:49
And here we're peering
through three kilometers of ice.
100
277498
2756
04:52
And there are sophisticated, interesting,
electromagnetic reasons for that,
101
280278
3840
04:56
but let's say for now that ice
is basically the perfect target for radar,
102
284142
4151
05:00
and radar is basically
the perfect tool to study ice sheets.
103
288317
3228
05:04
These are the flight lines
104
292641
1279
05:05
of most of the modern airborne
radar-sounding profiles
105
293944
3044
05:09
collected over Antarctica.
106
297012
1714
05:10
This is the result
of heroic efforts over decades
107
298750
2970
05:13
by teams from a variety of countries
and international collaborations.
108
301744
3625
05:17
And when you put those together,
you get an image like this,
109
305672
2857
05:20
which is what the continent
of Antarctica would look like
110
308553
2706
05:23
without all the ice on top.
111
311283
1346
05:25
And you can really see the diversity
of the continent in an image like this.
112
313958
4532
05:30
The red features
are volcanoes or mountains;
113
318514
2412
05:32
the areas that are blue
would be open ocean
114
320950
2110
05:35
if the ice sheet was removed.
115
323084
1580
05:36
This is that giant spatial scale.
116
324688
2634
05:39
However, all of this
that took decades to produce
117
327807
3001
05:42
is just one snapshot of the subsurface.
118
330832
3002
05:46
It does not give us any indication
of how the ice sheet is changing in time.
119
334220
4213
05:51
Now, we're working on that,
because it turns out
120
339338
2417
05:53
that the very first radar observations
of Antarctica were collected
121
341779
3449
05:57
using 35 millimeter optical film.
122
345252
2378
06:00
And there were thousands
of reels of this film
123
348021
2191
06:02
in the archives of the museum
of the Scott Polar Research Institute
124
350236
3254
06:05
at the University of Cambridge.
125
353514
1502
06:07
So last summer, I took
a state-of-the-art film scanner
126
355040
2581
06:09
that was developed for digitizing
Hollywood films and remastering them,
127
357645
3556
06:13
and two art historians,
128
361225
1151
06:14
and we went over to England,
put on some gloves
129
362400
2218
06:16
and archived and digitized
all of that film.
130
364642
2514
06:19
So that produced two million
high-resolution images
131
367744
3095
06:22
that my group is now working
on analyzing and processing
132
370863
3198
06:26
for comparing with contemporary
conditions in the ice sheet.
133
374085
2944
06:29
And, actually, that scanner --
I found out about it
134
377458
2392
06:31
from an archivist at the Academy
of Motion Picture Arts and Sciences.
135
379874
3386
06:35
So I'd like to thank the Academy --
136
383284
2524
06:37
(Laughter)
137
385832
2245
06:40
for making this possible.
138
388101
1318
06:41
(Laughter)
139
389443
1055
06:42
And as amazing as it is
140
390522
1697
06:44
that we can look at what was happening
under the ice sheet 50 years ago,
141
392243
3636
06:47
this is still just one more snapshot.
142
395903
2682
06:50
It doesn't give us observations
143
398609
2117
06:52
of the variation at the annual
or seasonal scale,
144
400750
3173
06:55
that we know matters.
145
403947
1336
06:57
There's some progress here, too.
146
405926
1564
06:59
There are these recent ground-based
radar systems that stay in one spot.
147
407514
3524
07:03
So you take these radars
and put them on the ice sheet
148
411062
2613
07:05
and you bury a cache of car batteries.
149
413699
1890
07:07
And you leave them out there
for months or years at a time,
150
415613
2810
07:10
and they send a pulse down
into the ice sheet
151
418447
2112
07:12
every so many minutes or hours.
152
420583
1498
07:14
So this gives you
continuous observation in time --
153
422105
2407
07:16
but at one spot.
154
424958
1150
07:18
So if you compare that imaging to the 2-D
pictures provided by the airplane,
155
426418
4390
07:22
this is just one vertical line.
156
430832
1857
07:25
And this is pretty much
where we are as a field right now.
157
433498
2856
07:28
We can choose between
good spatial coverage
158
436378
2658
07:31
with airborne radar sounding
159
439060
1493
07:32
and good temporal coverage in one spot
with ground-based sounding.
160
440577
3809
07:36
But neither gives us what we really want:
161
444410
2311
07:38
both at the same time.
162
446745
1341
07:40
And if we're going to do that,
163
448753
1437
07:42
we're going to need totally new ways
of observing the ice sheet.
164
450214
3007
07:45
And ideally, those should be
extremely low-cost
165
453245
2721
07:47
so that we can take lots
of measurements from lots of sensors.
166
455990
3235
07:51
Well, for existing radar systems,
167
459871
2143
07:54
the biggest driver of cost
is the power required
168
462038
3044
07:57
to transmit the radar signal itself.
169
465106
2297
08:00
So it’d be great if we were able
to use existing radio systems
170
468187
3295
08:03
or radio signals
that are in the environment.
171
471506
2722
08:06
And fortunately, the entire field
of radio astronomy
172
474252
2849
08:09
is built on the fact that there
are bright radio signals in the sky.
173
477125
3785
08:12
And a really bright one is our sun.
174
480934
2301
08:15
So, actually, one of the most exciting
things my group is doing right now
175
483259
3460
08:18
is trying to use the radio emissions
from the sun as a type of radar signal.
176
486743
3587
08:22
This is one of our field tests at Big Sur.
177
490354
2187
08:24
That PVC pipe ziggurat is an antenna stand
some undergrads in my lab built.
178
492565
4158
08:29
And the idea here
is that we stay out at Big Sur,
179
497100
2983
08:32
and we watch the sunset
in radio frequencies,
180
500107
2438
08:34
and we try and detect the reflection
of the sun off the surface of the ocean.
181
502569
4561
08:39
Now, I know you're thinking,
"There are no glaciers at Big Sur."
182
507585
3796
08:43
(Laughter)
183
511405
1085
08:44
And that's true.
184
512514
1158
08:45
(Laughter)
185
513696
1180
08:46
But it turns out that detecting
the reflection of the sun
186
514900
3700
08:50
off the surface of the ocean
187
518624
1358
08:52
and detecting the reflection
off the bottom of an ice sheet
188
520006
2802
08:54
are extremely geophysically similar.
189
522832
1741
08:56
And if this works,
190
524597
1199
08:57
we should be able to apply the same
measurement principle in Antarctica.
191
525820
3405
09:01
And this is not
as far-fetched as it seems.
192
529249
2040
09:03
The seismic industry has gone through
a similar technique-development exercise,
193
531313
3753
09:07
where they were able to move
from detonating dynamite as a source,
194
535090
3130
09:10
to using ambient seismic noise
in the environment.
195
538244
2489
09:12
And defense radars use TV signals
and radio signals all the time,
196
540757
3833
09:16
so they don't have to transmit
a signal of radar
197
544614
2579
09:19
and give away their position.
198
547217
1651
09:21
So what I'm saying is,
this might really work.
199
549280
2598
09:23
And if it does, we're going to need
extremely low-cost sensors
200
551902
3202
09:27
so we can deploy networks of hundreds
or thousands of these on an ice sheet
201
555128
3589
09:30
to do imaging.
202
558741
1151
09:31
And that's where the technological stars
have really aligned to help us.
203
559916
3606
09:35
Those earlier radar systems I talked about
204
563546
2404
09:37
were developed by experienced
engineers over the course of years
205
565974
3633
09:41
at national facilities
206
569631
1349
09:43
with expensive specialized equipment.
207
571004
1976
09:45
But the recent developments
in software-defined radio,
208
573354
2890
09:48
rapid fabrication and the maker movement,
209
576268
2246
09:50
make it so that it's possible
for a team of teenagers
210
578538
2952
09:53
working in my lab over the course
of a handful of months
211
581514
2642
09:56
to build a prototype radar.
212
584180
1445
09:58
OK, they're not any teenagers,
they’re Stanford undergrads,
213
586045
2809
10:00
but the point holds --
214
588878
1647
10:02
(Laughter)
215
590549
1424
10:03
that these enabling technologies
are letting us break down the barrier
216
591997
3303
10:07
between engineers who build instruments
and scientists that use them.
217
595324
3811
10:11
And by teaching engineering students
to think like earth scientists
218
599590
3941
10:15
and earth-science students
who can think like engineers,
219
603555
2678
10:18
my lab is building an environment in which
we can build custom radar sensors
220
606257
4233
10:22
for each problem at hand,
221
610514
1610
10:24
that are optimized for low cost
and high performance
222
612148
3437
10:27
for that problem.
223
615609
1468
10:29
And that's going to totally change
the way we observe ice sheets.
224
617101
3477
10:32
Look, the sea level problem and the role
of the cryosphere in sea level rise
225
620998
5081
10:38
is extremely important
226
626103
1585
10:39
and will affect the entire world.
227
627712
1674
10:41
But that is not why I work on it.
228
629815
2088
10:44
I work on it for the opportunity
to teach and mentor
229
632458
3115
10:47
extremely brilliant students,
230
635597
1787
10:49
because I deeply believe
that teams of hypertalented,
231
637804
3109
10:52
hyperdriven, hyperpassionate young people
232
640937
2492
10:55
can solve most of the challenges
facing the world,
233
643453
2547
10:58
and that providing the observations
required to estimate sea level rise
234
646577
4012
11:02
is just one of the many such problems
they can and will solve.
235
650613
3690
11:06
Thank you.
236
654768
1152
11:07
(Applause)
237
655944
2642

▲Back to top

ABOUT THE SPEAKER
Dustin Schroeder - Radio glaciologist
Dustin Schroeder develops and uses geophysical radar to study Antarctica, Greenland and the icy moons of Jupiter.

Why you should listen

Dustin Schroeder draws on techniques and approaches from defense technologies, telecommunication, resource exploration and radio astronomy to understand the evolution and stability of ice sheets and their contributions to sea level rise. He is an assistant professor of geophysics and (by courtesy) of electrical engineering at Stanford University where he is also an affiliate of the Woods Institute for the Environment. He has participated in three Antarctic field seasons with the ICECAP project and NASA’s Operation Ice Bridge.

Schroeder is a Science Team Member on the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) instrument on NASA's Europa Clipper Mission and the Mini-RF instrument on NASA's Lunar Reconnaissance Orbiter (LRO). He is also the Chair of the Earth and Space Sciences Committee for the National Science Olympiad.

More profile about the speaker
Dustin Schroeder | Speaker | TED.com